Process of preparing manganese-steel ingots for rolling.



WINFIELD S. POTTER, OF NEW YORK, N. Y.

PRGCESS 0F PREPARING MANGANESE-STEEL INGOTS FOR ROLLING.

935,3?(2. at Drawing.

Specification of Letters Patent. Application filed June 16, 192.0 Serial No. 587,331.

Patented Nov. 8, 1910.

To all whom it may concern:

Be it known that I, VVINFIELD S. POTTER, a citizen of the United States, residing at New York city, New York, and whose postofi'ice ddress is No. 30 Church street, New York city, New York, have invented certain new and useful lmprovments in Processes for Preparing Manganese-Steel Ingots for Rolling; and I do hereby declare the followiron are lined with a layer of silicious ganing to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to the casting and the heat treatment of ingots of manganese steel and more particularly to a method of obtaining the ingots in such a physical condition that the metal will withstand rolling when it is heated to a high temperature.

I have discovered that when the steel is heated to temperatures lying within a range approximately between 640 C. and 720 C. and held for a considerable time within this range, or when the temperature is slowly raised or lowered through this range, that a reconstruction or recrystallization of the mass of steel may be eiiected. This reconstruction at temperatures between 640 C. and 720 Y may be applied to ingots cast in the ordinary manner in iron molds having heavy walls, but the time required to break down in this manner the dendritic structures occurring in ingots which have been so cast is objectionably long. For this reason I prefer to cast the ingots in molds having inner walls or surfaces in contact with the pouredin metal, which are of such a charactor; that the heat of casting is slowly abstracted from the ingots. To this end the inner walls of the molds may be made up largely of materials which are refractory and which conduct heat slowly, such as sand or ganister. Good results may also be obtained by casting the ingots in molds having thin inner walls of metal, iuwhich case the index wall of the mold maybe backed with a layer of material which is a poor conductor of heat, such as fine sand or asbestos, and this non-conducting layer may in turn be supported by a casing of metal. Bycasting in'molds of this nature, the crystall ne arrangement of the metal in the outer portion of the ingots is of a very much more favorable c aracter than the pronounced dendritic structure found in the outer portion of ingots of manganese steel cast in heavy iron molds.

In carrying my invention into practice, the manganese steel of the desired composition is cast into molds which for the purposes of illustration may consist of cast iron shells made in two halves, the division being on a plane passing through the longitudinal axes of the molds, which shells of cast ister, five or six; inches in thickness. The in 'gots may be tapered or parallel. If the ingots are tapered, the'molds may be removed by lifting, or if the ingots are made parallel, they may be separated from the molds by opening the split molds on the plane of division, as, for example, by releasing any suitable fastening mechanism, such as bolts or clamps'provided for the purpose.

After casting, the ingots are preferably allowed to remain in the molds until they have setand'until they have cooled to an average temperature between 600 C. and 800 C. The molds are then removed. from the ingots and the ingots placed in soaking pits or heating furnaces, whichpits will at this time have a temperature of about 700 C. The temperature of the soaking it and the contained ingots is now equalized at some point within the critical range lying between 640 C. and 720 0.,

and is then preferably slowly raised and lowered through the critical range until the freezing structures in the steel have been removed and the desirable reconstruction effected. For example, if the temperature in the soaking pit and the ingots has been equalized at 750 (1, the furnace and its contents will be slowly cooled to about 600 (1., and the temperature then slowly raised to about 750 C. The slow cooling and slow reheating mayvthen be repeated, if necessary, to complete the recrystallization of the steel. to ingots will now usually be heated to a much hi her temperature for rolling, although w en the desirable reconstruction has once been executed, the ingots may be cooled 0E and subsequently reheated for rolling. Proceeding in the usual manner, the temperature is raised to and maintained g t/about 1150 C. until the ingots have this temperature throughout. The ingots are now removed from the furnace or soak ng pit and immediately rolled. If the greatest obtainable ductility is required, the ingots may be heated to about'l250 C. and held at this temperature until heated to 1250 C. throughout. In this case and in order to avoid crushing, the outer portion-oi the ingot must first be cooled to ll50 (1., for example, or lightly worked, and thereby somewhat cooled and strengthened before any heavy reductions in the rolls are attempted, as set forth in my 7U. Patent No. 938,893, dated November 2,1909.

Having now fully described m invention, what I claim and desire to secure by Letters Patent is I Y 1. The process of preparing ingots of manganese steel for rolling, which consists 'incasting1 the ingot, equalizing the temperature wit in the ingot, slowly passing the temperature through a range lying between 600? C. and 750 C. until reconstruct-ion is efiected, and finally raising the temperature temperature through a range lying between 600 C. and 7 50 C. until reconstruction'is effected, and finally raising the temperature of the ingot to about 1150 C. for rolling; substantially as described,

In testimony whereof I aifix my-signature;

in presence of two witnesses.

WINFIELD s. POTTER Witnesses:

ELSA M, ,GEILFUSS, WILLIAM H. DAVIS.: 

